It is commonplace for publicly accessible facilities to provide soap dispensers in washrooms and other areas. Many dispensers have reservoirs that are open to the atmosphere. Such reservoirs are easily and inexpensively refilled from bulk soap stored in bottles or jugs. However, studies have shown that over time soap containers open to the atmosphere generate unsanitary bio-films. Soap used from these containers actually deposits germs onto the hands of the user during use. Even after cleaning the reservoir, remediation studies have determined that bio-films regenerate despite using strong oxidizers like bleach.
To overcome the detriments of open top dispensers, the reservoir in some dispensers is not refilled when the system is replenished. These systems are designed to receive disposable refill units produced in a sanitary environment. When empty of product, the whole reservoir is replaced along with the accompanying nozzle and pump. In this way, every part wetted by soap is disposed of when the dispenser is replenished. This greatly reduces and/or eliminates the germination of bio-films. However, determining how much soap is remaining in the reservoir, and when to replace it, can be difficult. If the reservoir is replaced before it is empty, then product is wasted. If the dispenser runs out of soap, then users are unable to clean their hands.
What is needed is a way of conveniently replenishing soap reservoirs without exposing the reservoir or the product to ambient air and without interrupting service or running out of product. The embodiments of the invention described herein obviate the aforementioned problems.